[Bug target/112431] RISC-V GCC-15 feature: Support register overlap on widen RVV instructions

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112431

--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Lehua Ding <lhtin@gcc.gnu.org>:

https://gcc.gnu.org/g:a23415d7572774701d7ec04664390260ab9a3f63

commit r14-6055-ga23415d7572774701d7ec04664390260ab9a3f63
Author: Juzhe-Zhong <juzhe.zhong@rivai.ai>
Date:   Fri Dec 1 15:00:27 2023 +0800

    RISC-V: Support highpart register overlap for widen vx/vf instructions

    This patch leverages the same approach as vwcvt.

    Before this patch:

    .L5:
            add     a3,s0,s1
            add     a4,s6,s1
            add     a5,s7,s1
            vsetvli zero,s0,e32,m4,ta,ma
            vle32.v v16,0(s1)
            vle32.v v12,0(a3)
            mv      s1,s2
            vle32.v v8,0(a4)
            vle32.v v4,0(a5)
            nop
            vfwadd.vf       v24,v16,fs0
            vfwadd.vf       v16,v12,fs0
            vs8r.v  v16,0(sp)                -----> spill
            vfwadd.vf       v16,v8,fs0
            vfwadd.vf       v8,v4,fs0
            nop
            vsetvli zero,zero,e64,m8,ta,ma
            vfmv.f.s        fa4,v24
            vl8re64.v       v24,0(sp)       -----> reload
            vfmv.f.s        fa5,v24
            fcvt.lu.d a0,fa4,rtz
            fcvt.lu.d a1,fa5,rtz
            vfmv.f.s        fa4,v16
            vfmv.f.s        fa5,v8
            fcvt.lu.d a2,fa4,rtz
            fcvt.lu.d a3,fa5,rtz
            add     s2,s2,s5
            call    sumation
            add     s3,s3,a0
            bgeu    s4,s2,.L5

    After this patch:

    .L5:
            add     a3,s0,s1
            add     a4,s6,s1
            add     a5,s7,s1
            vsetvli zero,s0,e32,m4,ta,ma
            vle32.v v4,0(s1)
            vle32.v v28,0(a3)
            mv      s1,s2
            vle32.v v20,0(a4)
            vle32.v v12,0(a5)
            vfwadd.vf       v0,v4,fs0
            vfwadd.vf       v24,v28,fs0
            vfwadd.vf       v16,v20,fs0
            vfwadd.vf       v8,v12,fs0
            vsetvli zero,zero,e64,m8,ta,ma
            vfmv.f.s        fa4,v0
            vfmv.f.s        fa5,v24
            fcvt.lu.d a0,fa4,rtz
            fcvt.lu.d a1,fa5,rtz
            vfmv.f.s        fa4,v16
            vfmv.f.s        fa5,v8
            fcvt.lu.d a2,fa4,rtz
            fcvt.lu.d a3,fa5,rtz
            add     s2,s2,s5
            call    sumation
            add     s3,s3,a0
            bgeu    s4,s2,.L5

            PR target/112431

    gcc/ChangeLog:

            * config/riscv/vector.md: Support highpart overlap for vx/vf.

    gcc/testsuite/ChangeLog:

            * gcc.target/riscv/rvv/base/pr112431-22.c: New test.
            * gcc.target/riscv/rvv/base/pr112431-23.c: New test.
            * gcc.target/riscv/rvv/base/pr112431-24.c: New test.
            * gcc.target/riscv/rvv/base/pr112431-25.c: New test.
            * gcc.target/riscv/rvv/base/pr112431-26.c: New test.
            * gcc.target/riscv/rvv/base/pr112431-27.c: New test.